You can play Nids comfortably up to 1850 - they still do fine at 1000 points as there are a few rather sick builds. HQs are not a problem at 100 - take a Terv, Prime or PoM depending on how you want to build your list. Doom on his own at 1250 and less is sick. Back to Shrikes - they need cover. I play them with dual boneswords/rending joined by my Parasite and shielded by Gargoyles. It is decent at lower point levels. But two or three Terv lists can be even better.